The stem-and-leaf display below gives the test scores for the 16 students in Prof. Jones' economics class. Use the display to answer the questions that follow.
Test scores
5 |4
6 |1 4 4
7 |3 4 4 7 8 9
8 |7 9
9 |1 1 4 6
Key: 5|4 means a score of 54.
(a) What was the lowest score in the 70s?
(b) What was the highest score overall?
(c) How many students scored in the 50s?